U.S. patent number 9,340,316 [Application Number 14/172,038] was granted by the patent office on 2016-05-17 for poly(ethylene terephthalate)(apet) multilayer oxygen-scavenging containers and methods of making.
This patent grant is currently assigned to Mullinix Packages, Inc.. The grantee listed for this patent is Mullinix Packages, Inc.. Invention is credited to Luther A. Gross, Gary Klimek, Matt Schiffli, Brian Schmitz, Boh C. Tsai.
United States Patent |
9,340,316 |
Schmitz , et al. |
May 17, 2016 |
Poly(ethylene terephthalate)(APET) multilayer oxygen-scavenging
containers and methods of making
Abstract
An oxygen-scavenging multi-layer container and methods of
making, controlling, and using the same are disclosed.
Inventors: |
Schmitz; Brian (Fort Wayne,
IN), Gross; Luther A. (Churubusco, IN), Tsai; Boh C.
(Inverness, IL), Schiffli; Matt (Fort Wayne, IN), Klimek;
Gary (Fort Wayne, IN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Mullinix Packages, Inc. |
Fort Wayne |
IN |
US |
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Assignee: |
Mullinix Packages, Inc. (Fort
Wayne, IN)
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Family
ID: |
51486573 |
Appl.
No.: |
14/172,038 |
Filed: |
February 4, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20140251993 A1 |
Sep 11, 2014 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61774109 |
Mar 7, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B
27/285 (20130101); B65D 1/40 (20130101); B32B
27/20 (20130101); B65D 81/267 (20130101); B32B
27/08 (20130101); B32B 27/36 (20130101); B32B
2307/306 (20130101); B32B 2439/70 (20130101); B32B
2307/704 (20130101); B32B 2250/24 (20130101); B32B
2264/105 (20130101); B32B 2270/00 (20130101); B32B
2307/702 (20130101); Y10T 156/10 (20150115); B32B
2307/7244 (20130101) |
Current International
Class: |
B65D
1/40 (20060101); B65D 81/26 (20060101); B32B
27/08 (20060101); B32B 27/20 (20060101); B32B
27/28 (20060101); B32B 27/36 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0083826 |
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Jul 1983 |
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EP |
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2009032418 |
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Mar 2009 |
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WO |
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Other References
Roodvoets, Enhanced Gas Barriers in Thermoformed Trays,
Thermoforming Quarterly, pp. 1-3 and 8-10, Second Quarter 2013.
cited by applicant .
OxyClear.TM. Barrier Resin a New Oxygen Scavenging PET, Invista
Polymer & Resins, The Packaging Conference--Las Vegas, 2010.
cited by applicant .
PCT International Search Report and the Written Opinion, Appln. No.
PCT/US2014/21102, filed Mar. 6, 2014, date of mailing Jun. 6, 2014.
cited by applicant .
PCT International Search Report and the Written Opinion, Appln. No.
PCT/US14/21108, filed Mar. 6, 2014, date of mailing Jun. 5, 2014.
cited by applicant.
|
Primary Examiner: Miggins; Michael C
Attorney, Agent or Firm: MacMillan, Sobanski & Todd,
LLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This is application which claims the priority to U.S. Provisional
Application No. 61/774,109, filed Mar. 7, 2013, the entire
disclosures of which are expressly incorporated herein by
reference.
Claims
What is claimed is:
1. A multi-layer container comprising: an outer layer; an inner
layer; and at least one middle layer interposed therebetween; the
middle layer including a blend of: at least one oxygen-scavenging
component, at least one catalyst-containing concentrate, and a
polymer consisting essentially of polyethylene terephthalate (PET);
wherein the middle layer contains at least one catalyst transition
metal up to about 3%, by weight, of the multi-layer container; and
wherein at least one of the outer layer and the inner layer
comprises a polymer consisting essentially of amorphous
poly(ethylene terephthalate) (APET).
2. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate includes one or more oxidation
catalyst.
3. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate depends on the scavenging
component.
4. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate depends on the ability to
co-process (e.g., co-extrusion or co-injection) with the scavenging
component.
5. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate includes a transition metal
selected from cobalt, copper, rhodium, ruthenium, palladium,
tungsten, osmium, cadmium, silver, tantalum, hafnium, vanadium,
titanium, chromium, nickel, zinc, and manganese.
6. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate includes a transition metal in the
form of a salt.
7. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate includes a transition metal in the
form of a salt, and wherein counter ions for the metal include one
or more of carboxylates, including neodecanoates, octanoates,
stearates, acetates, naphthalates, lactates, maleates,
acetylacetonates, linoleates, oleates, palminates, 2-ethyl
hexanoates, oxides, borides, carbonates, chlorides, dioxides,
hydroxides, nitrates, phosphates, sulfates, and, silicates.
8. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate includes at least one of cobalt
stearate or cobalt acetate that is present in a total concentration
not exceeding about 3%, by weight, of the multi-layer
container.
9. The multi-layer container of claim 1, wherein the
catalyst-containing concentrate comprises an oxidation catalyst
blended with PET.
10. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 5:95.
11. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 10:90.
12. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 20:80.
13. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 30:70.
14. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 40:60.
15. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 50:50.
16. The multi-layer container of claim 1, wherein a ratio of
oxygen-scavenging component to catalyst-containing concentrate is
about 60:40.
17. The multi-layer container of claim 1, wherein a total
concentration of oxygen-scavenging component in the middle layer is
at least about 10%, by weight, of the multi-layer container.
18. The multi-layer container of claim 1, wherein a total
concentration of oxygen-scavenging component in the middle layer is
at least about 5%, by weight, of the multi-layer container.
19. The multi-layer container of claim 1, wherein a total
concentration of oxygen-scavenging component in the middle layer is
at least about 3%, by weight, of the multi-layer container.
20. The multi-layer container of claim 1, wherein a total
concentration of oxygen-scavenging component in the middle layer is
at least about 2%, by weight, of the multi-layer container.
21. The multi-layer container of claim 1, wherein a total
concentration of oxygen-scavenging component in the middle layer is
at least about 1%, by weight, of the multi-layer container.
22. The multi-layer container of claim 1, wherein a total
concentration of oxygen-scavenging component in the middle layer is
at least about 0.5%, by weight, of the multi-layer container.
23. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of no
greater than about 3 cc O.sub.2/100 in.sup.2dayatm.
24. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of no
greater than about 2 cc O.sub.2/100 in.sup.2dayatm.
25. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of no
greater than about 1.5 cc O.sub.2/100 in.sup.2dayatm.
26. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of no
greater than about 1 cc O.sub.2/100 in.sup.2dayatm.
27. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of no
greater than about 0.5 cc O.sub.2/100 in.sup.2dayatm.
28. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of no
greater than about 0 cc O.sub.2/100 in.sup.2dayatm.
29. The multi-layer container of claim 1, wherein the outer layer
of the multi-layer container has an oxygen permeation rate of less
than about 0 cc O.sub.2/100 in.sup.2dayatm.
30. The multi-layer container of claim 1, wherein the multi-layer
container has an oxygen headspace absorption effect of about 0 cc
O.sub.2 ingress after about 5 days.
31. The multi-layer container of claim 1, wherein the multi-layer
container has an oxygen headspace absorption effect of less than
about 0 cc O.sub.2 ingress after about 5 days.
32. The multi-layer container of claim 1, wherein the multi-layer
container has an oxygen headspace absorption effect of more than
about 0.3% headspace oxygen reduction after about 20 days.
33. The multi-layer container of claim 1, wherein the multi-layer
container has an oxygen absorption effect of that increases over
time after about 5 days after manufacturing of the multi-layer
container.
34. The multi-layer container of claim 1, wherein the middle layer
has an oxygen-scavenging component to catalyst-containing
concentrate ratio of greater than about 0.05.
35. The multi-layer container of claim 1, wherein substantially no
adhesive material is interposed between the middle layer and the
outer layer and/or the middle layer and the inner layer.
36. The multi-layer container of claim 1, wherein both the outer
layer and the inner layer comprise an amorphous poly(ethylene
terephthalate) polymer (APET).
37. The multi-layer container of claim 1, wherein the blend of the
oxygen-scavenging polymer and the catalyst-containing concentrate
is present in the middle layer at about a 50:50 ratio.
38. The multi-layer container of claim 1, wherein the blend of the
one oxygen-scavenging polymer and the catalyst-containing
concentrate is present in the middle layer at about a 50:50 ratio;
and wherein the middle layer has a thickness of about 0.5 mil.
39. The multi-layer container of claim 1, wherein the blend of the
one oxygen-scavenging polymer and the catalyst-containing
concentrate is present in the middle layer at about a 50:50 ratio;
and, the multi-layer container having an oxygen absorption of about
50 cc O.sub.2, per gram of oxygen-scavenging polymer, present in
the multi-layer container.
40. The multi-layer container of claim 1, wherein the outer layer
has a thickness of about 1 mil or more.
41. The multi-layer container of claim 1, wherein the
oxygen-scavenging component in the middle layer is present in an
amount of at least about 0.5%, by weight, of the multi-layer
container.
42. The multi-layer container of claim 1, wherein the
oxygen-scavenging component in the middle layer is present in an
amount of at least about 1%, by weight, of the multi-layer
container.
43. The multi-layer container of claim 1, wherein the
oxygen-scavenging component in the middle layer is present in an
amount of at least about 2%, by weight, of the multi-layer
container.
44. The multi-layer container of claim 1, wherein the
oxygen-scavenging component in the middle layer is present in an
amount of at least about 2%, by weight, of the multi-layer
container.
45. The multi-layer container of claim 1, wherein a ratio of the
oxygen-scavenging component present to catalyst-containing
concentrate in the middle layer is about 5:95.
46. The multi-layer container of claim 1, wherein the
oxygen-scavenging component present is at least about 2% or
greater, by weight, of the multi-layer container.
47. The multi-layer container of claim 1, wherein the multi-layer
container has an oxygen absorption of at least about 50 cc O.sub.2,
per gram of oxygen-scavenging component.
48. A multi-layer container comprising: an outer layer; an inner
layer; and at least one middle layer interposed therebetween; the
middle layer including a blend of: at least one oxygen-scavenging
component, at least one catalyst-containing concentrate, and a
polymer consisting essentially of polyethylene terephthalate (PET);
wherein the middle layer contains at least one catalyst transition
metal up to about 3%, by weight, of the multi-layer container; the
multi-layer container having: i) a ratio of oxygen-scavenging
component to catalyst-containing concentrate of about 5:95; ii) a
total concentration of oxygen-scavenging component in the middle
layer of at least about 0.5%, by weight, of the multi-layer
container; iii) an oxygen permeation rate of the outer layer no
greater than about 3 cc O.sub.2/100 in.sup.2dayatm; iv) an oxygen
headspace absorption effect of about 0 cc O.sub.2 ingress after
about 5 days; and v) an oxygen absorption effect of that increases
over time after about 5 days after manufacturing of the multi-layer
container.
49. A method of making the multi-layer container, comprising: a)
providing a middle layer including a blend of: at least one
oxygen-scavenging component; at least one catalyst-containing
concentrate that contains at least one catalyst transition metal up
to about 3%, by weight, of the multi-layer container; and, a
polymer consisting essentially of polyethylene terephthalate (PET);
and b) interposing the middle layer between at least one outer
layer and at least one inner layer without the use of an adhesive
material; wherein at least one of the outer layer and the inner
layer comprises a polymer consisting essentially of amorphous
poly(ethylene terephthalate) (APET).
Description
TECHNICAL FIELD
Described herein are multi-layer containers usable in the plastics
packaging industry. Further disclosed are methods of making and
using multi-layer containers with oxygen-scavenging properties and
methods of controlling the oxygen scavenging incubation period of
multi-layer containers.
BACKGROUND OF THE INVENTION
In food and beverage packaging, metal cans and glass bottles were
traditionally the preferred packages. With the introduction of
polypropylene (PP) and ethylene vinyl alcohol copolymer (EVOH)
multi-layer containers, PP/EVOH containers, and poly(ethylene
terephthalate) PET containers in the 1980s, a portion of the
metal-based and glass-based packages were replaced by
plastics-based packages.
The shelf life of a plastic package is determined by the amount of
oxygen that permeates into the package. A container made from
amorphous poly(ethylene terephthalate) (APET) typically has a shelf
life of three to six months. A container made from crystalline
poly(ethylene terephthalate) (CPET) typically has a shelf life of
five to ten months. Because both APET and CPET containers have a
PET recycling code ("1"), which is considered most environmental
friendly due to the successful development of recycling
infrastructure over the years; it would be desirable to improve the
oxygen barrier of these materials so they can be used extensively
in packaging for food and other oxygen-sensitive products. Many
unsuccessful attempts have been made at incorporating an effective
oxygen scavenger into the walls of PET containers such that the
container has zero or negative oxygen permeation to compete with
the metal-based and glass-based packages.
Not only do commercially available oxygen scavenging containers
fall short of achieving zero or negative oxygen permeation, but
they have several other drawbacks. For instance, many articles of
active packaging suffer from two oxygen absorption initiation
problems: (1) short or no induction period and (2) long or infinite
induction period. When the induction period is too short, it allows
for ambient oxygen absorption during inventory before the container
is filled (i.e., before oxygen absorption is desired). On the other
hand, when the induction period is too long, they require some sort
of triggering agent, such as ultraviolet light or water, to begin
scavenging. A further disadvantage of these containers is that such
materials may require thick sidewalls, which adds to cost.
Many commercially available oxygen-scavenging containers begin to
scavenge oxygen immediately. Without an incubation period, the
expensive oxygen scavenger is wasted during the inventory period.
It is common in the industry for containers to be in transportation
from supplier to user for a couple months. It is therefore
desirable to keep the container from scavenging oxygen during
inventory and start oxygen scavenging immediately when the
container is filled with product.
It would be beneficial to develop a plastics-based package for food
or beverages with less oxygen permeation and more controlled oxygen
scavenging. There remains a need for packaging materials that
perform these feats in a more efficient and cost-effective manner.
It would be beneficial to improve the shelf life of containers made
specifically from PET-based materials. It would be further
beneficial to discover efficient methods of manufacturing such
containers.
There is no admission that the background art disclosed in this
section legally constitutes prior art.
BRIEF SUMMARY OF THE INVENTION
Disclosed herein is a multi-layer container usable in plastics
packaging for food and beverages. The multi-layer container
comprises an outer layer and an inner layer, each including a
polymeric resin, and a middle layer.
Further disclosed is a method of using a multi-layer container
described herein.
Various objects and advantages of this invention will become
apparent to those skilled in the art from the following detailed
description of the preferred embodiment, when read in light of the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing oxygen ingress into empty containers over
time. The graph shows negative oxygen permeation of an empty
multilayer container comprised of 60% CPET/20%(10% BB-10.TM.+90%
Merge.TM.)/20% APET, compared to linearly increasing oxygen
permeation in a control container.
FIG. 2 is a graph displaying barrier properties of retorted,
water-filled containers. The graph compares the percent of oxygen
ingress over time between a CPET multi-layer container (comprised
of 60% CPET/20% (10% BB-10.TM. component+90% Merge.TM.
component)/20% APET), a control container, and a PP/EVOH container.
The containers were retorted at 260.degree. F. for 45 minutes.
FIG. 3 is a graph showing percent oxygen absorption over time, for
a multi-layer container (comprised of 60% CPET/20% (20% BB-10.TM.
component+80% Merge.TM. component)/20% APET) not designed to have a
significant incubation period.
FIG. 4 is a graph showing percent oxygen absorption over time, for
a multi-layer container (comprised of 60% CPET/20% (40% BB-10.TM.
component+60% Merge.TM. component)/20% APET), designed to have an
incubation period of about 50 days.
FIG. 5A is a graph showing the effect of the scavenging component
absorption of a multi-layer container, an APET control container,
and a monolayer container, where the total concentration of
scavenging polymer in the multi-layer container and monolayer
container is 1%.
FIG. 5B is a table of the data shown in FIG. 5A.
FIG. 6A is a graph showing the oxygen absorption of a multi-layer
container, an APET control container, and a monolayer container,
where the total concentration of scavenging polymer in the
multi-layer container and monolayer container is 2%.
FIG. 6B is a table of the data shown in FIG. 6A.
FIG. 7A is a graph showing the oxygen absorption of a multi-layer
container, an APET control container, and a monolayer container,
where the total concentration of scavenging polymer in the
multi-layer container and monolayer container is 3%.
FIG. 7B is a table of the data shown in FIG. 7A.
FIG. 8A is a graph showing the oxygen permeation of a multi-layer
container, an APET control container, and a monolayer container,
where the total concentration of scavenging polymer in the
multi-layer container and monolayer container shown is 1%.
FIG. 8B is a table of the data shown in FIG. 8A.
FIG. 9A is a graph showing the oxygen permeation of a multi-layer
container, an APET control container, and a monolayer container,
where the total concentration of scavenging polymer in the
multi-layer container and monolayer container shown is 2%.
FIG. 9B is a table of the data shown in FIG. 9A.
FIG. 10A is a graph showing the oxygen permeation of a multi-layer
container, an APET control container, and a monolayer container,
where the total concentration of scavenging polymer in the
multi-layer container and monolayer container shown is 3%.
FIG. 10B is a table of the data shown in FIG. 10A.
FIG. 11A is a graph showing oxygen absorption as a function of
BB-10.RTM. component concentration in a middle layer of an APET
multi-layer container. Absorption capacity tends to increase as the
concentration of BB-10.TM. component in the middle layer
increases.
FIG. 11B is a table of the data shown in FIG. 11A.
FIG. 12 is a table showing the data shown in FIG. 11A and FIG. 11B
as a function of time, showing a total BB-10.TM. component
concentration in the container sidewall and the absorption capacity
(cc/g of BB-10.TM. component).
FIG. 13A is a graph showing the effect of layer structure on oxygen
permeation, where the thickness of the outer layer in the APET
multi-layer containers shown is 2.2 mils.
FIG. 13B is a table of the data shown in FIG. 13A.
FIG. 14A is a graph showing the effect of layer structure on oxygen
permeation, where the thickness of the outer layer in the APET
multi-layer containers shown is 4.4 mils.
FIG. 14B is a table of the data shown in FIG. 14A.
FIG. 15A is a graph showing the effect of layer structure on oxygen
permeation, where the thickness of the outer layer in the APET
multi-layer containers shown is 6.6 mils.
FIG. 15B is a table of the data shown in FIG. 15A.
FIG. 16 is a table summarizing the effect of the outer layer
permeation rate on the headspace oxygen absorption for the data
shown in FIGS. 13A-13B, 14A-14B, and 15A-15B.
FIG. 17A is a graph showing the effect of the scavenging
polymer-to-catalyst concentrate ratio on the oxygen absorption
continues over time for multi-layer container (#10446) having the
layers: 12 mil CPET/4 mil blend (10% BB-10.TM. component+90%
Merge.TM. component)/4 mil APET; where the container has 2% total
BB-10.TM. component, and for multi-layer container (#Oxy 2) having
the layers: 12 mil CPET/2 mil blend (20% BB-10.TM. component+80%
Merge.TM. component)/6 mil APET; where the container has 2% total
BB-10.TM. component, for over 100 days.
FIG. 17B is a table of the data shown in FIG. 17A.
FIG. 18A is a graph showing the effect of the storage time-on the
oxygen absorption over time for multi-layer container (#10446)
having the layers: 12 mil CPET/4 mil blend (10% BB-10.TM.
component+90% Merge.TM. component)/4 mil APET; where the container
has 2% total BB-10.TM. component.
FIG. 18B is a table of the data shown in FIG. 18A.
FIG. 19A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy2)
having the layers: 12 mil CPET/2 mil blend (20% BB-10.TM.
component+80% Merge.TM. component)/6 mil APET; where the container
has 2% total BB-10.TM. component.
FIG. 19B is a table of the data shown in FIG. 19A.
FIG. 20A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy 3)
having the layers: 12 mil CPET/4 mil blend (20% BB-10.TM.
component+80% Merge.TM. component)/4 mil APET; where the container
has 4% total BB-10.TM. component.
FIG. 20B is a table of the data shown in FIG. 20A.
FIG. 21A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy 4)
having the layers: 12 mil CPET/2.7 mil blend (30% BB-10.TM.
component+70% Merge.TM. component)/5.3 mil APET; where the
container has 4% total BB-10.TM. component.
FIG. 21B is a table of the data shown in FIG. 21A.
FIG. 22A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy 5)
having the layers: 12 mil CPET/2 mil blend (40% BB-10.TM.
component+60% Merge.TM. component)/6 mil APET; where the container
has 4% total BB-10.TM. component.
FIG. 22B is a table of the data shown in FIG. 22A.
FIG. 23 is table summarizing the data of FIGS. 18A-18B, FIGS.
19A-19B, FIGS. 20A-20B, FIGS. 21A-21B and FIGS. 22A-22B showing the
effect of varying the scavenging component-to-catalyst concentrate
ratio on the oxygen absorption, where data was gathered from each
container beginning after two different storage times.
FIG. 24A is a graph showing the effect of varying the storage time
on the oxygen permeation for a multi-layer container having the
layers: 6.6 mil APET/2.2 mil blend (25% BB-10.RTM. component+75%
Merge.RTM. component/2.2 mil APET, where the container has 5% total
BB-10.RTM. component; data was gathered from each container after
two different storage times.
FIG. 24B is a table of the data shown in FIG. 24A.
FIG. 25A is a graph showing the effect of varying the storage time
on the oxygen permeation for a multi-layer container having the
layers: 6.6 mil APET/1.7 mil blend (33% BB-10.RTM. component+67%
Merge.RTM. component/2.7 mil APET, where the container has 5% total
BB-10 component; data was gathered from each container after two
different storage times.
FIG. 25B is a table of the data shown in FIG. 25A.
FIG. 26A is a graph showing the effect of varying the storage time
on the oxygen permeation for a multi-layer container having the
layers: 6.6 mil APET/1.13 mil blend (50% BB-10.RTM. component+50%
Merge.RTM. component/3.3 mil APET, where the container has 5% total
BB-10.RTM. component; data was gathered from each container after
two different storage times.
FIG. 26B is a table of the data shown in FIG. 26A.
FIG. 27 is a table summarizing the data of FIGS. 24A-24B, FIGS.
25A-25B and FIGS. 26A-26B, showing the effect of varying the
scavenging polymer-to-catalyst concentrate ratio on the transition
time of positive oxygen permeation to negative oxygen permeation
for a multi-layer container having the layers.
DETAILED DESCRIPTION OF THE INVENTION
Described herein is an oxygen-scavenging multi-layer container or
articles for use in the plastics packaging industry. In certain
embodiments, the multi-layer container has zero oxygen permeation
for more than three years. In addition, the composition of the
multi-layer container allows the multi-layer container to reduce
headspace oxygen after being sealed. Also, described herein is a
method of controlling the incubation period of the multi-layer
container's oxygen scavenging activity.
As used herein, "polymer" may be used to refer to homopolymers,
copolymers, interpolymers, etc. Likewise, a "copolymer" may refer
to a polymer comprising two monomers or to a polymer comprising
three or more monomers.
As used herein, "middle" or "intermediate" is defined as the
position of one layer of a multi-layer article wherein such layer
lies between two other identified layers. In certain embodiments,
the intermediate layer may be in direct contact with either or both
of the two identified layers (e.g., outer layer and inner layer).
In other embodiments, one or more additional layers may also be
present between the intermediate layer and either or both of the
two identified layers.
As used herein, the middle, or active, layer includes at least one
oxygen scavenging component and at least one catalyst-containing
concentrate. It is to be understood herein that the terms "middle
layer," "intermediate" and "active layer" may be used
interchangeably, and further that the "middle layer" while
generally understood to be interposed between an outermost layer
and at an innermost layer, such "middle layer" need not necessarily
be exactly centered between the outer layer and the inner layer.
That is, in multi-layer containers that contain an even number of
layers, the middle layer may be positioned either closer to the
outer layer, or to the inner layer, depending on the end-use
requirements of the multi-layer container.
Any of the layers in the multi-layer container may comprise a
plurality of polymeric resins and may include any of several
additives, and numerous embodiments of the multi-layer container
are disclosed herein. In addition, several characteristics of the
multi-layer container are controllable by adjusting the thickness
ratio of the layers, the total concentration of at least one oxygen
scavenging component, the ratio of scavenging component to a
catalyst-containing concentrate and/or the identity of specific
resins in each layer.
In a broad aspect, the multi-layer container is a modified, or
active, polymeric resin container. The container comprises an outer
layer, a middle layer, and an inner layer. In certain embodiments.
The middle layer is generally not thicker than either of the outer
or inner layers. In one embodiment, the thickness of the layers,
from outer to inner, is in a 60:20:20 ratio. Other thickness ratios
are possible. For example, the layers may be in a 40:20:40
thickness ratio, a 60:13:27 thickness ratio, or a 60:10:30
thickness ratio. In certain embodiments, the multi-layer container
disclosed herein has a total sidewall thickness (meaning the
thicknesses of each layer combined) of about 10 mils to about 30
mils, though other thicknesses are possible.
The outer layer and inner layer are each comprised of a polymeric
resin. Either layer may comprise a single resin or a blend of
multiple resins. Suitable resins for use in the inner or outer
layers are PET, PP, EVOH, high-density polyethylene (HDPE),
polyvinyl chloride (PVC), low-density polyethylene (LDPE),
polystyrene (PS), acrylic, nylon, polycarbonate, polylactic acid,
acrylonitrile butadiene styrene (ABS), or mixtures thereof. In
certain embodiments, the polymeric resin is crystalline PET (CPET).
In one embodiment, referred to herein as a CPET multi-layer
container, the outer layer comprises CPET and the inner layer
comprises APET.
The middle, or active, layer of the multi-layer container includes
at least one oxygen-scavenging component (also referred to herein
as "scavenging polymer" and "scavenging component") and at least
one catalyst-containing concentrate. The scavenging component and
catalyst-containing concentrate are blended together in a desired
ratio to form the middle layer. The scavenging component is present
in a concentration ranging from about 1% to about 50%, by weight,
of the total container. In certain embodiments, the scavenging
component is present in a concentration ranging from about 1% to
about 10%, by weight, of the total container. As the examples below
demonstrate, the amount of oxygen absorbed by the multi-layer
container is determined by the total amount of the scavenging
component in the multi-payer container.
In another aspect, provided herein is a method of increasing the
absorption of oxygen by a multi-layer container, the method
comprising increasing the concentration of scavenging component
present in the middle layer.
In a particular embodiment, the multi-layer container comprising an
outer layer, an inner layer, and at least one middle layer
interposed therebetween; the middle layer including a blend of: i)
at least one oxygen-scavenging component, and ii) at least one
catalyst-containing concentrate; wherein middle layer contains at
least one catalyst transition metal up to about 3% by weight of the
multi-layer container.
In certain embodiments, the catalyst-containing concentrate
includes one or more oxidation catalysts.
In certain embodiments, the catalyst-containing concentrate depends
on the makeup of the scavenging component.
In certain embodiment, the catalyst-containing concentrate depends
on the ability to co-process (e.g. co-extrusion or co-injection)
with the scavenging component.
In certain embodiments, the catalyst-containing concentrate
includes a transition metal selected from cobalt, copper, rhodium,
ruthenium, palladium, tungsten, osmium, cadmium, silver, tantalum,
hafnium, vanadium, titanium, chromium, nickel, zinc, and
manganese.
In certain embodiments, the catalyst-containing concentrate
includes a transition metal in the form of a salt.
In certain embodiments, the catalyst-containing concentrate
includes a transition metal in the form of a salt, and wherein
counter ions for the metal include one or more of carboxylates,
including neodecanoates, octanoates, stearates, acetates,
naphthalates, lactates, maleates, acetylacetonates, linoleates,
oleates, palminates, and 2-ethyl hexanoates; oxides; borides;
carbonates; chlorides; dioxides; hydroxides; nitrates; phosphates;
sulfates; and, silicates.
In certain embodiments, the catalyst-containing concentrate
includes at least one of cobalt stearate or cobalt acetate that is
present in a total concentration not exceeding about 3%, by weight,
of the multi-layer container.
In certain embodiments, catalyst-containing concentrate is
comprised of an oxidation catalyst blended with a polymeric
resin.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 5:95.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 10:90.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 20:80.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 30:70.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 40:60.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 50:50.
In certain embodiments, a ratio of oxygen-scavenging component to
catalyst-containing concentrate is about 60:40.
In certain embodiments, a total concentration of oxygen-scavenging
component in the middle layer is at least about 10%, by weight, of
the multi-layer container.
In certain embodiments, a total concentration of oxygen-scavenging
component in the middle layer is at least about 5%, by weight, of
the multi-layer container
In certain embodiments, a total concentration of oxygen-scavenging
component in the middle layer is at least about 3%, by weight, of
the multi-layer container.
In certain embodiments, a total concentration of oxygen-scavenging
component in the middle layer is at least about 2%, by weight, of
the multi-layer container.
In certain embodiments, a total concentration of oxygen-scavenging
component in the middle layer is at least about 1%, by weight, of
the multi-layer container.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of no greater than about 3
cc O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of no greater than about 2
cc O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of no greater than about
1.5 cc O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of no greater than about 1
cc O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of no greater than about
0.5 cc O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of no greater than about 0
cc O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the outer layer of the multi-layer
container has an oxygen permeation rate of less than about 0 cc
O.sub.2/100 in.sup.2dayatm.
In certain embodiments, the multi-layer container has an oxygen
headspace absorption effect of about 0 cc O.sub.2 ingress after
about 5 days.
In certain embodiments, the multi-layer container has an oxygen
headspace absorption effect of less than about 0 cc O.sub.2 ingress
after about 5 days.
In certain embodiments, the multi-layer container has an oxygen
headspace absorption effect of more than about 0.3% headspace
oxygen reduction after about 20 days.
In certain embodiments, the multi-layer container has an oxygen
absorption effect of that increases over time after about 5 days
after manufacturing of the multi-layer container.
In certain embodiments, the middle layer has an oxygen-scavenging
component to catalyst-containing concentrate ratio of greater than
about 0.05.
In certain embodiments, substantially no adhesive material is
interposed between the middle layer and the outer layer and/or the
middle layer and the inner layer.
In certain embodiments, a multi-layer container comprises an outer
layer, an inner layer, and at least one middle layer interposed
therebetween; the middle layer including a blend of: i) at least
one oxygen-scavenging component, and ii) at least one
catalyst-containing concentrate; wherein middle layer contains at
least one catalyst transition metal up to about 3%, by weight, of
the multi-layer container; the multi-layer container having: i) a
ratio of oxygen-scavenging component to catalyst-containing
concentrate of about 5:95; ii) a total concentration of
oxygen-scavenging component in the middle layer of at least about
1%, by weight, of the multi-layer container; iii) an oxygen
permeation rate of the outer layer no greater than about 3 cc
O.sub.2/100 in.sup.2dayatm; iv) an oxygen headspace absorption
effect of about 0 cc O.sub.2 ingress after about 5 days; and v) an
oxygen absorption effect of that increases over time after about 5
days after manufacturing of the multi-layer container.
Also described herein is a method of making the multi-layer
container, comprising: providing a middle layer including a blend
of: i) at least one oxygen-scavenging component; and, ii) at least
one catalyst-containing concentrate that contains at least one
catalyst transition metal up to about 3%, by weight, of the
multi-layer container; and, interposing the middle layer between at
least one outer layer and at least one inner layer without the use
of an adhesive material.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET).
In certain embodiments, both the outer layer and the inner layer
are comprised of an amorphous poly(ethylene terephthalate) polymer
(APET).
In certain embodiments, at least one of the inner layer and the
outer layer is comprised of APET, and the blend of the
oxygen-scavenging polymer and the catalyst-containing concentrate
is present in the middle layer at about a 50:50 ratio.
In certain embodiments, at least one of the inner layer and the
outer layer is comprised of APET, and the blend of the one
oxygen-scavenging polymer and the catalyst-containing concentrate
is present in the middle layer at about a 50:50 ratio; and wherein
the middle layer has a thickness of about 0.5 mil.
In certain embodiments, at least one of the inner layer and the
outer layer is comprised of APET, the blend of the one
oxygen-scavenging polymer and the catalyst-containing concentrate
is present in the middle layer at about a 50:50 ratio; and, the
multi-layer container having an oxygen absorption of about 50 cc
O.sub.2, per gram of oxygen-scavenging polymer, present in the
multi-layer container.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the outer layer has a thickness
of about 1 mil or more.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the oxygen-scavenging polymer in
the middle layer is present at least about 0.5%, by weight, of the
multi-layer container.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the oxygen-scavenging component
to catalyst-containing concentrate in the middle layer is present
at least about 1%, by weight, of the multi-layer container.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the oxygen-scavenging polymer in
the middle layer is present at least about 2%, by weight, of the
multi-layer container.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the oxygen-scavenging component
polymer in the middle layer is present at least about 2%, by
weight, of the multi-layer container.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and a ratio of the oxygen-scavenging
component present to catalyst-containing concentrate in the middle
layer is about a 5:95 ratio.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the oxygen-scavenging component
present at least about 2% or greater, by weight, of the multi-layer
container.
In certain embodiments, at least one of the outer layer and the
inner layer is comprised of an amorphous poly(ethylene
terephthalate) polymer (APET), and the multi-layer container has an
oxygen absorption of at least about 50 cc O.sub.2, per gram of
oxygen-scavenging component.
Oxygen Scavenger Component
In one non-limiting example, the oxygen scavenger component
generally comprises a copolyester ether having a polyether segment
comprising a poly(tetramethylene-co-alkylene ether), where the
alkylene is selected from the group consisting of ethylene,
propylene and butylene. The molecular weight of the polyether
segment can be in the range of from about 200 g/mole to about 5,000
g/mole. The copolyester ether can contain the polyether segment in
a range of from about 15%, by weight, to about 95%, by weight. The
copolyester ether further comprises a poly(alkylene oxide)glycol
selected from the group including poly(ethylene oxide)glycol,
poly(trimethylene oxide)glycol, poly(tetramethylene oxide)glycol,
poly(pentamethylene oxide)glycol, poly(hexamethylene oxide)glycol,
poly(heptamethylene oxide)glycol, poly(octamethylene oxide)glycol,
and poly(alkylene oxide)glycols derived from cyclic ether monomers
where the alkylene is selected from the group including ethylene,
propylene and butylene. The mole percent of alkylene oxide in the
polyether segment can be in the range of from about 20 mole percent
to about 75 mole percent.
In one embodiment, the two-component formulation may comprise of a
catalyst-containing concentrate and an oxygen-scavenging resin sold
under the trademark OxyClear.RTM. manufactured by Auriga Polymers
Inc., 4235 South Stream Blvd., Charlotte, N.C. 28217. In certain
embodiments, the catalyst-containing concentrate is referred to
herein as "Merge" or "Merge 2310.TM." and the oxygen scavenging
component is referred to herein as "BB-10.TM." or "Merge 3500.TM."
which are manufactured by Auriga Polymers, Inc.
In certain embodiments where the particular embodiments where a
BB-10.TM. component is at least part of the oxygen scavenging
component, the BB-10.RTM. component can be present in a total
concentration of at least about 1.0%, by weight, of the multi-layer
container. Also, in certain embodiments where the BB-10.TM.
component is the oxygen scavenging component, the multi-layer
container does not comprise a reducing sulfite salt or an
oxidizable metal such as iron, zinc, copper, aluminum, or tin. In
certain embodiments where BB-10.TM. component is at least part of
the oxygen scavenging component, the multi-layer container does not
comprise an electrolyte component. In certain embodiments where
BB-10.TM. component is at least part of the oxygen scavenging
component, the multi-layer container does not comprise a
water-absorbent binder.
It is to be understood that, in other embodiment, other scavenging
components may be used. For instance, the scavenging component may
include a partially aromatic polyamide with a copolyester
comprising a metal sulfonate salt. Also, in certain other
embodiments, suitable oxygen scavenger components can include
oxidizable polymers.
Catalyst-Containing Concentrates
In certain embodiments, the catalyst-containing concentrate may
comprise one or more suitable oxidation catalysts. Also, in certain
embodiments, the particular catalyst-containing concentrate that is
useful in the multi-layer container can be varied, depending on the
particular oxygen scavenging component that is used. In particular
embodiments, the oxidation catalyst generally comprises a
transition metal selected from cobalt, copper, rhodium, ruthenium,
palladium, tungsten, osmium, cadmium, silver, tantalum, hafnium,
vanadium, titanium, chromium, nickel, zinc, and manganese. The
metal may be in the form of a salt. Suitable counter ions for the
metal may include carboxylates (such as neodecanoates, octanoates,
stearates, acetates, naphthalates, lactates, maleates,
acetylacetonates, linoleates, oleates, palminates, or 2-ethyl
hexanoates), oxides, borides, carbonates, chlorides, dioxides,
hydroxides, nitrates, phosphates, sulfates and silicates. In
particular embodiments, the oxidation catalyst comprises cobalt
stearate or cobalt acetate. In a particular embodiment, the
oxidation catalyst (such as cobalt stearate or cobalt acetate) is
present in a total concentration not exceeding 3%, by weight, of
the multi-layer container.
It is to be understood that the oxidation catalyst is generally
blended with a polymeric resin in order to form the
catalyst-containing concentrate. In certain embodiments, the
polymeric resin is compatible with both the outer CPET layer and
the inner layer such that no adhesive material is needed when
forming the multi-layer container.
In one embodiment, the catalyst-containing concentrate can be a
material sold under the trade names Merge and Merge-2310
manufactured by Auriga Polymers, Inc.
Method of Forming "Active or Middle," Layers
In one method for forming the middle layer, the oxygen scavenging
component and the catalyst-component concentrate are blended
together in an extruder. No triggering agent is necessary to begin
oxygen scavenging. The oxygen scavenger component and the
catalyst-containing concentrate may be blended with one or more
additional polymeric resins to form an active layer for the
oxygen-scavenging multi-layer containers. Suitable additional
resins include CPET, APET, PP, EVOH, HDPE, PVC, LDPE, PS, acrylic,
nylon, polycarbonate, polylactic acid, ABS, or mixtures thereof. In
embodiments where the oxygen scavenger component and the
catalyst-containing concentrate are not blended with additional
resins, the middle layer has an oxygen scavenger
component-to-catalyst-containing concentrate ratio ranging from
about 1:99, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:60, 40:60,
50:50, 55:45, 60:40. 65:35, 70:30, 75:30, 80:20, percent, by
weight, of the middle layer. In particular examples stated herein,
the ratio is about 5:95, 10:90, 20:80, 25:75, 30:70, 33:67, 40:60,
or 50:50 percent, by weight, of the middle layer. Other scavenging
component-to-concentrate ratios are possible; however, in certain
embodiments, the multi-layer containers disclosed herein has a
scavenging component-to-concentrate ratio of at least 2:98 percent,
by weight, of the middle layer.
In addition, any of the layers (outer, middle and/or inner) in the
multi-layer container may comprise additional additives. Examples
of such possible additives are dyes, pigments, fillers, branching
agents, reheat agents, anti-blocking agents, anti-oxidants,
anti-static agents, biocides, blowing agents, coupling agents,
flame retardants, heat stabilizers, impact modifiers, UV and
visible light stabilizers, crystallization aids, lubricants,
plasticizers, drying agents, processing aids, acetaldehydes or
other scavengers, and slip agents, or mixtures thereof. Other
additives are possible. In addition, any of the layers in the
container, including the layer comprising the scavenging component
and the catalyst-containing concentrate, may be foamed. Any
suitable polymeric foaming technique, such as bead foaming or
extrusion foaming, can be utilized to accomplish the foaming. A
foamed resin layer can be adhered to a solid resin layer by a
suitable method. Also, any of the layers may further comprise a
passive barrier such as a metalized polyolefin, a silica-coated
polyester, or aluminum foil. Further, any layer may comprise an
anti-microbial agent to help preserve foods, or silicone to prevent
sticking during processing.
Methods of Making Multilayer Containers (or Articles)
To manufacture the multi-layer container disclosed herein, the
layers are blended together at the desired thickness of each layer
into a multi-layered material, such as a film, sheet, or preform,
through, for example, coextrusion, coinjection, coating or
lamination. The multi-layered material is then stretch blow molded,
"melt-to-mold" or thermoformed into a multi-layer container or
other fabricated article using either single-stage or multi-stage
blow molding or single-stage or multi-stage thermoforming.
Also described herein is a method of producing an oxygen-scavenging
multi-layer container. The method includes the steps of producing
an active layer by blending at least one oxygen-scavenging
component with at least one catalyst-containing concentrate at a
specific ratio and extruding the active layer. The active layer can
be extruded adjacent one or more other polymeric resins to form a
multi-layer container. In certain embodiments, the multi-layer
container can be formed by a suitable process (such as, but not
limited to thermoforming, stretch blow molding and melt-to-mold
processing). In general, the melt-to-mold process, a molten,
crystallizable polyester composition film is thermoformed and
crystallized by cooling to a temperature between the polyester Tg
and the polyester Tm. In general, thermoforming includes the step
of pulling a plastic sheet from a roll over a die or mold of the
object to be formed, then sealing the sheet along the periphery of
the mold. The plastic sheet is then heated to render it pliable,
and pressure is applied to the sheet forcing the sheet into the
mold. Alternatively a vacuum is drawn from below the sheet
evacuating the air in the space between the mold surface and the
sheet surface thereby drawing the surface of the sheet into the
shape of the mold. Additionally, pressure and vacuum can be used
together to form the article. When the heated sheet is expanded
into and held against the contours of the mold and allowed to cool,
the sheet retains the details of the mold upon removal.
Further disclosed herein is a method of controlling the oxygen
scavenging incubation period of a multi-layer container. The method
involves adjusting the scavenging component-to-concentrate ratio in
the active layer of a multi-layer container.
Examples of suitable other fabricated articles in addition to
multi-layer containers include, but are not limited to, films,
sheets, tubing, pipes, fibers, thermoformed articles, or flexible
bags. The multi-layer articles can also be used on as layers,
coatings, bottle cap liners, sheet inserts, gaskets, sealants, and
the like.
Non-limiting examples of products which can be packaged in such
multi-layer containers include not only food and beverage, but also
other oxygen sensitive materials such as pharmaceuticals, medical
products, corrodible metals or products such as electronic devices,
and the like.
It is also to be understood that in most embodiments, the
multi-layer container made by this process does not need an
external triggering mechanism such as ultraviolet light or water in
order to begin oxygen scavenging.
Crystalline Poly(Ethylene Terephthalate) (CPET)
In certain embodiments, at least one of the outer and/or inner
layers of the multi-layer contain is comprised of a crystalline
poly(ethylene terephthalate) CPET polymer material. In many cases,
CPET multi-layer containers, and articles made therefrom, are
opaque because of the crystallinity of the polymer. Also due to the
crystallinity, CPET multi-layer containers have high heat
resistance, are suitable for retort sterilization at temperatures
as high as desired, such as 260.degree. F. or higher, and can be
used in microwave ovens or conventional ovens (400.degree. F.).
In addition, CPET multi-layer containers are also suitable for use
in hot fill sterilization processes (185-194.degree. F.) and other
sterilization processes. By contrast, embodiments comprising APET
in both the inner and outer layer are glass-clear but have low heat
resistance. CPET is also less subject to deformation under stress
than APET. A variety of fabricated multi-layer containers
comprising both CPET and APET is possible due to the variability of
suitable materials, concentrations, and thicknesses. For example,
in certain embodiments, a multi-layer container comprises CPET in
the outer layer, APET in the inner layer, and has a total thickness
of about 10 mils to about 30 mils with a layer thickness ratio from
outer to inner of any of 60:20:20, 60:13:27, 60:15:25, 60:10:30,
40:20:40, or 20:20:60. Effectively, the multi-layer container
disclosed herein comprising CPET is a high-heat oxygen barrier.
In certain embodiments, the synthesis of CPET starts with either an
esterification reaction between terephthalic acid and ethylene, or
a transesterification reaction between ethylene glycol and dimethyl
terephthalate. The monomer product is then polymerized into PET
through a condensation process with either water or methanol as the
byproduct. Once polymerized, the PET material is crystallized. In
one method, the PET material is submerged in water, heated to an
elevated temperature known as the glass transition temperature, and
not quenched rapidly. This causes the polymer to turn opaque due to
the formation of crystallized aggregates of un-oriented polymer.
Crystallization of the heated PET material can also be
stress-induced. If heated PET material is dried too rapidly,
however, it emerges in an amorphous state as APET.
One feature of the multi-layer container described herein is that
the multi-layer container's incubation period before oxygen
absorption begins can be adjusted by altering the composition of
the middle layer, or active layer, that contains the scavenging
component and catalyst-containing concentrate.
It is to be noted that, for particular embodiments, the incubation
period can be lengthened or shortened by varying the ratio of
scavenging component to catalyst-containing concentrate in the
middle layer. That is, the less amount of catalyst present in the
middle layer, the longer the incubation time of the multi-layer
container's oxygen scavenging. As an example, a multi-layer
container having a layer thickness ratio of 60:20:20 with CPET in
the outer layer, APET in the inner layer, and a scavenging
component-to-concentrate ratio of 20:80 percent by weight of the
middle layer, begins to absorb oxygen without a notable incubation
period. An otherwise identical multi-layer container having a
scavenging component-to-concentrate ratio of 40:60 percent by
weight of the middle layer begins to absorb oxygen after an
incubation period of about 50 days.
In certain embodiments, to ensure that the container does not
scavenge during inventory (i.e., before being used by the food
manufacturer), the scavenging component-to-concentrate ratio can be
in the range of about 2-to-about-98. Thus, disclosed herein is a
method of controlling the incubation period of an oxygen-scavenging
multi-layer container, where the method does not need to rely on
the use of water or ammonium salts.
Various articles, such as packaging containers for food or
beverages, can be fabricated from the multi-layer container. These
articles can have negative oxygen permeation for up to three years
and can have customized incubation periods adjusted for the
approximate amount of time between production of the multi-layer
containers and filling of the multi-layer containers. For example,
a multi-layer container that will sit for 50 days in a warehouse
before being filled could be made to have a 50-day incubation
period, as explained above. This way, the multi-layer containers
can be kept inactive during inventory, thereby reducing the amount
of oxygen scavenger necessary. In addition, the articles do not
need adhesive and do not show delamination.
In certain embodiments where the cost of the scavenging component
is high, it is desired to maximize the oxygen absorption capacity
per gram of the scavenging component. In certain non-limiting
embodiments, where the BB-10.TM. component is at least a part of
the scavenging component, an oxygen absorption capacity of 50 cc
per gram of BB-10.TM. component is desirable. As the examples below
demonstrate, increasing the concentration of scavenging component
in the middle layer results in an increase in the oxygen absorption
capacity per gram of scavenging component. For example, where
oxygen absorption of 55 cc per gram of BB-10.TM. component is
accomplished, the BB-10.TM. component is present at least about 5%,
by weight, of the middle layer.
Further disclosed herein is a method of reducing the headspace
oxygen of a multi-layer container. If the oxygen absorption rate is
quicker than the oxygen permeation rate through the outer layer,
then the container's headspace oxygen becomes even lower than the
original value at the time of filling. Headspace oxygen reduction
is desirable because such reduction may eliminate the costly
practice of gas flushing the headspace after filling the container
with product.
In certain non-limiting embodiments where the scavenging component
is the BB-10.TM. component, the oxygen permeation rate through the
outer layer is less than 2 cc/100 in.sup.2dayatm, which provides a
desirable reduction in headspace oxygen. In one particular
embodiment, a multi-layer, container includes at least: an outer
layer comprising APET at least about 3.6 mils thick, and an outer
layer comprising CPET at least about 1.5 mils thick.
The duration of headspace oxygen reduction is a function of the
scavenging component concentration. The method of reducing the
headspace oxygen of a multi-layer container can include adjusting
the thickness of the outer layer, the total amount of the
scavenging component, or the concentration of the scavenging
component.
EXAMPLES
Certain embodiments of the present invention are defined in the
Examples herein. It should be understood that these Examples, while
indicating preferred embodiments of the invention, are given by way
of illustration only. From the above discussion and these Examples,
one skilled in the art can ascertain the essential characteristics
of this invention, and without departing from the spirit and scope
thereof, can make various changes and modifications of the
invention to adapt it to various usages and conditions.
Some of the following examples reference trial or other identifying
numbers. Because many parameters and characteristics of the
multi-layer container disclosed herein are customizable, many
alternative embodiments of the multi-layer container are possible.
A series of 17 multi-layer containers in accordance with the
present disclosure were manufactured and tested in a variety of
manners in comparison with two control containers and three
monolayer containers.
For ease of reference when reading the following examples, the
composition of the various embodiments of the multi-layer
container, along with the control and monolayer containers,
described in the following examples are given below: Trial #1: 11
mil APET monolayer container, 0% total BB-10.RTM. component. Trial
#2: 11 mil monolayer container with 3% BB-10.TM., 17% Merge.TM. and
80% APET, 3% total BB-10.TM. component. Trial #3: 6.6 mil APET/2.2
mil (15% BB-10.TM.+85% Merge.TM.)/2.2 mil APET, 3% total BB-10.TM.
component. Trial #4: 4.4 mil APET/2.2 mil (15% BB-10.TM.+85%
Merge.TM.)/4.4 mil APET, 3% total BB-10.TM. component. Trial #5:
2.2 mil APET/2.2 mil (15% BB-10.TM.+85% Merge.TM.)/6.6 mil APET, 3%
total BB-10.TM. component. Trial #6: 11 mil monolayer structure
with 2% BB-10.TM., 18% Merge.TM. and 80% APET, 2% total BB-10.TM.
component. Trial #7: 6.6 mil APET/2.2 mil (10% BB-10.TM.+90%
Merge.TM.)/2.2 mil APET, 2% total BB-10.TM. component. Trial #8:
4.4 mil APET/2.2 mil (10% BB-10.TM.+90% Merge.TM.)/4.4 mil APET, 2%
total BB-10.TM. component. Trial #9: 2.2 mil APET/2.2-mil (10%
BB-10.TM.+90% Merge.TM.)/6.6 mil APET, 2% total BB-10.TM.
component. Trial #10: 11 mil monolayer structure with 1% BB-10.TM.,
19% Merge.TM. and 80% APET, 1% total BB-10.TM. component. Trial
#11: 6.6 mil APET/2.2 mil (5% BB-10.TM.+95% Merge.TM.)/2.2 mil
APET, 1% total BB-10.TM. component. Trial #12: 4.4 mil APET/2.2 mil
(5% BB-10.TM.+95% Merge.TM.)/4.4 mil APET, 1% total BB-10.TM.
component. Trial #13: 2.2 mil APET/2.2 mil (5% BB-10.TM.+95%
Merge.TM.)/6.6 mil APET, 1% total BB-10.TM. component. Trial #14:
6.6 mil APET/2.2 mil (25% BB-10.TM.+75% Merge.TM.)/2.2 mil APET, 5%
total BB-10.TM. component. Trial #15: 6.6 mil APET/1.7 mil (33%
BB-10+67% Merge.TM.)/2.7 mil APET, 5% total BB-10.TM. component.
Trial #16: 6.6 mil APET/1.1 mil (50% BB-10.TM.+50% Merge.TM.)/3.3
mil APET, 5% total BB-10.TM. component.
CPET Control: 20 mil CPET, 0% total BB-10.TM. component. #10446: 12
mil CPET/4 mil (10% BB-10.TM.+90% Merge.TM.)/4 mil APET, 2% total
BB-10.TM. component. #Oxy 2: 12 mil CPET/2 mil (20% BB-10.TM.+80%
Merge.TM.)/6 mil APET, 2% total BB-10.TM. component. #Oxy 3: 12 mil
CPET/4 mil (20% BB-10.TM.+80% Merge.TM.)/4 mil APET, 4% total
BB-10.TM. component. #Oxy 4: 12 mil CPET/2.7 mil (30% BB-10.TM.+70%
Merge.TM.)/5.3 mil APET, 4% total BB-10.TM. component. #Oxy 5: 12
mil CPET/2 mil (40% BB-10.TM.+60% Merge.TM.)/6 mil APET, 4% total
BB-10.TM. component.
Example 1
Oxygen Ingress
A CPET multi-layer container having a volume of 93 cc, a surface
area of 15.25 in.sup.2, and a sidewall thickness of 20 mils was
fabricated and tested side by side with a CPET control container.
An OxyDot.RTM. oxygen sensor was glued on the clear inner surface
of a glass plate inside the containers, and the containers were
then sealed. During sealing, the containers were flushed with
nitrogen to 1% headspace oxygen.
As shown in FIG. 1, the headspace oxygen of the control container
increased after 1,000 days from 1.37% to 5.56%, while that of the
CPET multi-layer container decreased from 1.03% to 0.26%. These
results clearly demonstrate that the CPET multi-layer container is
superior not only to any plastics-based containers, but also to
metal cans and glass bottles. A good result was achieved with a
very high surface to volume ratio (16.4 in.sup.2/100 cc or 15.25
in.sup.2/93 cc) multi-layer container having a fairly thin side
wall (20 mils).
Example 2
Barrier Properties
A CPET multi-layer container having a volume of 297 cc, a surface
area of 35.3 in.sup.2, and a sidewall thickness of 19 mils, was
filled with about 90% water to have about 10% empty headspace. A
SiO.sub.x-coated bather lidding film with an OxyDot.RTM. oxygen
sensor glued on the inner surface was heat-sealed on the container.
The same procedure was followed for a CPET control container and a
PP/EVOH container, to be tested side by side with the CPET
multi-layer container. During water filling, the containers were
flushed with nitrogen to 5% headspace oxygen. The containers were
then retorted at 260.degree. F. for 45 minutes.
As shown by FIG. 2, the control container and the PP/EVOH container
showed a steady increase of oxygen concentration while the CPET
multi-layer container showed a steady decrease of oxygen
concentration. At day 20, the headspace oxygen change of the
PP/EVOH container, the control container, and the CPET multi-layer
container was +1.5%, +0.8%, and -0.3%, respectively. The poor
oxygen barrier property of the PP/EVOH container shortly after
retort is due to the retort shock effect; the retort causes high
moisture content in EVOH. As the barrier property of EVOH recovered
after about 80 days, the PP/EVOH container had lower oxygen
concentration than the control container. At day 320, the headspace
oxygen change of the control container, the PP/EVOH container, and
the CPET multi-layer container was +5.0%, +2.2%, and -4.0%,
respectively. This result clearly demonstrates that the CPET
multi-layer container is superior to the commercial PP/EVOH
container. Furthermore, the results show the headspace oxygen of
the CPET multi-layer container steadily decreases, in contrast to
perfect barrier packages such as metal cans or glass bottles, which
can only keep the headspace oxygen unchanged.
Example 3
Multi-Layer v Mono Layer
The oxygen absorption of a multi-layer container was compared to
that of a monolayer container. The container sidewall was
pulverized to fine particles and placed in a sealed glass
container. The oxygen concentration inside the glass container was
measured periodically by a non-invasive oxygen analyzer sold by
Oxysense Inc. The glass container containing an APET control
container sample remained at 21% oxygen while the multi-layer
container's oxygen absorption was lower.
As seen in FIGS. 5A-5B, FIGS. 6A-6B and FIGS. 7A-7B, the monolayer
containers containing BB-10.TM. component (trials #10, #6 and #2)
did not absorb oxygen at all, while the multi-layer containers
containing BB-10.TM. component (trials #12, #8 and #4) absorbed
oxygen. While not wishing to be bound by theory, it is now believed
by the inventors herein that the host APET polymer in the monolayer
container destroys the efficacy of the BB-10.TM.
component/Merge.TM. component oxygen scavenger completely.
Example 4
Oxygen Permeation
Oxygen permeation was compared between a multi-layer container, an
APET control container, and a monolayer container. The containers
were sealed with a glass plate in a low oxygen chamber. The initial
headspace oxygen inside the containers was about 1-2%. The
headspace oxygen concentration was measured periodically by a
non-invasive oxygen analyzer sold by Oxysense Inc. to obtain the
oxygen permeation rate. The oxygen permeation of the APET control
container and the monolayer container increased with time while the
multi-layer container's oxygen permeation was far lower, sometimes
negative.
As seen in FIGS. 8A-8B, FIGS. 9A-9B and FIGS. 10A-10B, the
monolayer container containing BB-10.RTM. component (trials #10, #6
and #2) did not absorb oxygen at all while the multi-layer
container containing BB-10.TM. component (trials #12, #8 and #4)
absorbed oxygen. The host APET polymer in the monolayer structure
destroyed the efficacy of the BB-10.TM. component/Merge.TM.
component oxygen scavenger completely. By incorporating the BB-10
Component.TM./Merge.TM. component oxygen scavenger in a separate
layer in the multi-layer container, the oxygen absorption efficacy
of the BB-10.TM. component/Merge.TM. component oxygen scavenger is
preserved.
Example 5
Oxygen Absorption Capacity
The concentration effect on oxygen absorption capacity was
determined. The sidewall of each of an APET control container and a
multi-layer container was pulverized to fine particles and placed
in a sealed glass container. The headspace oxygen of the glass
container containing the APET control container sample remained at
21% while that containing the multi-layer container was lower. The
percent reduction of the oxygen headspace can be converted to the
amount of oxygen absorbed. Since the amount of BB-10.TM. component
in each pulverized sample is known, one can calculate the oxygen
absorption capacity (cc/g of BB-10.TM. component). The steady state
values after 130 days are shown in FIG. 11A.
The oxygen absorption capacity of the BB-10.TM. component/Merge.TM.
component formulation increases with the BB-10.TM. component
concentration in the middle layer. In other words, for the same
amount of BB-10.TM. component, one can increase the efficacy of the
BB-10.TM. component/Merge.TM. component formulation by
concentrating BB-10.TM. component in a thin layer of a multi-layer
structure instead of dispersing BB-10.TM. component in a thick
monolayer structure.
In certain embodiments, since the particular oxygen scavenger
BB-10.TM. component is much more expensive than other components in
a plastic container, it is desired to maximize the oxygen
absorption capacity while using a lesser amount of the expensive
oxygen scavenger component in order to be cost competitive with
other barrier systems. In certain embodiments, an oxygen absorption
capacity of 50 cc per gram of BB-10.TM. component is desirable.
FIGS. 11A-11B and FIG. 12, show specific embodiments where the
BB-10.TM. component concentration in the middle layer is higher
than 5%, by weight.
Example 6
Headspace Oxygen Absorption
The effect of layer structure on headspace oxygen absorption was
determined by measuring oxygen permeation in containers with
varying layer structures. The containers were sealed with a glass
plate in a low oxygen chamber. The initial headspace oxygen inside
the containers was about 1-2%. The headspace oxygen concentration
was measured periodically by a non-invasive oxygen analyzer sold by
Oxysense Inc. to obtain the oxygen permeation rate. The headspace
oxygen of the APET control container increased with time while that
of the multi-layer container showed a reduced oxygen permeation
rate or even a negative permeation.
As seen in FIGS. 13A-13B, FIGS. 14A-14B and FIGS. 15A-15B, the APET
control #1 container did not absorb oxygen at all while the
multi-layer containers containing BB-10 Component.TM./Merge.TM.
component absorbed oxygen. Containers having a 2.2 mil APET outer
layer, a 4.4 mil APET outer layer, and a 6.6-mil APET outer layer
were also tested.
The effect of the outer layer permeation rate on the headspace
oxygen reduction is summarized in the table shown in FIG. 16.
From these results, it is determined that the oxygen permeation
rate through the outer layer should be less than 2 cc/100
in.sup.2dayatm for the BB-10.TM. component/Merge.TM. component
formulation to reduce the headspace oxygen inside a container.
Furthermore, the total BB-10.TM. component concentration is the
factor which determines the duration of oxygen headspace absorption
(e.g., #4, #8 vs. #12 in FIG. 14 and #3, #7 vs. #11 in FIG. 15).
The oxygen permeation rate is a function of material properties and
layer thickness. In one embodiment, in order to achieve the 2
cc/100 in.sup.2dayatm requirement, a 3 mil APET outer layer was
used, and a 1.5 mil CPET outer layer was sufficient.
Example 7
Scavenging Component/Catalyst Component Ratio in Multilayer
Container as Affecting Oxygen Absorption Incubation Time
The effect of the scavenging component-to-catalyst concentrate
ratio was studied by measuring the oxygen absorption of containers
with varying scavenging component-to-catalyst concentrate ratios.
The sidewalls of several containers were pulverized into fine
particles and placed in a sealed glass container. The oxygen
concentration inside the glass container was measured periodically
by a non-invasive oxygen analyzer sold by Oxysense Inc. The glass
container containing the APET control container sample remained at
21% while that containing the multi-layer container sample was
lower. The difference between 21% and that of the multi-layer
container is shown in FIGS. 17A-22B.
FIG. 17A is a graph showing the effect of the scavenging
component-to-catalyst concentrate ratio on the oxygen absorption
continues over time for multi-layer container (#10446) having the
layers: 12 mil CPET/4 mil blend (10% BB-10.TM. component+90%
Merge.TM. component)/4 mil APET; where the container has 2% total
BB-10.TM. component, and for multi-layer container (#Oxy 2) having
the layers: 12 mil CPET/2 mil blend (20% BB-10 component+80%
Merge.TM. component)/6 mil APET; where the container has 2% total
BB-10.TM. component, for over 100 days. FIG. 17B is a table of the
data shown in FIG. 17A.
FIG. 18A is a graph showing the effect of the storage time-on the
oxygen absorption over time for multi-layer container (#10446)
having the layers: 12 mil CPET/4 mil blend (10% BB-10.TM.
component+90% Merge.TM. component)/4 mil APET; where the container
has 2% total BB-10.TM. component. FIG. 18B is a table of the data
shown in FIG. 18A.
FIG. 19A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy2)
having the layers: 12 mil CPET/2 mil blend (20% BB-10.TM.
component+80% Merge.TM. component)/6 mil APET; where the container
has 2% total BB-10.TM. component. FIG. 19B is a table of the data
shown in FIG. 19A.
FIG. 20A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy 3)
having the layers: 12 mil CPET/4 mil blend (20% BB-10.TM.
component+80% Merge.TM. component)/4 mil APET; where the container
has 4% total BB-10.TM. component. FIG. 20B is a table of the data
shown in FIG. 8A.
FIG. 21A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy 4)
having the layers: 12 mil CPET/2.7 mil blend (30% BB-10.TM.
component+70% Merge.TM. component)/5.3 mil APET; where the
container has 4% total BB-10.TM. component. FIG. 21B is a table of
the data shown in FIG. 21A.
FIG. 22A is a graph showing the effect of the storage time on the
oxygen absorption over time for multi-layer container (#Oxy 5)
having the layers: 12 mil CPET/2 mil blend (40% BB-10.TM.
component+60% Merge.TM. component)/6 mil APET; where the container
has 4% total BB-10.TM. component. FIG. 22B is a table of the data
shown in FIG. 22A.
This experiment was first conducted 7 days after the containers
were made. The same experiment was then repeated 42 days after the
containers were made. From FIGS. 18A-22B, it is now shown that that
the containers, except Oxy 5, after 42-day storage absorb oxygen
immediately while those after 7-day storage have an incubation time
in oxygen absorption.
The incubation time based on the first experiment (7-day storage)
is summarized in the table shown in FIG. 23, summarizing the data
of FIGS. 18A-18B, FIGS. 19A-19B, FIGS. 20A-20B, FIGS. 21A-21B and
FIGS. 22A-22B showing the effect of varying the scavenging
component-to-catalyst concentrate ratio on the oxygen absorption
incubation time.
The incubation time increased with the BB-10.TM.
component/Merge.TM. component ratio. Container Oxy 5, which has a
40:60 BB-10.TM. component/Merge.TM. component ratio, had a 60-day
incubation time. The long incubation time of container Oxy 5 was
also confirmed by the second experiment. After 42-day storage,
container Oxy 5 still had a 20-day incubation time. Since the
incubation time of containers #10446, Oxy 2, Oxy 3, Oxy 4 and Oxy 5
were all less than 42 days, those containers showed no incubation
time during the second experiment.
Example 8
Scavenging Component/Catalyst Component Ratio in Multilayer
Container as Affecting Oxygen Permeation
The effect of varying scavenging polymer-to-concentrate ratio on
oxygen permeation was determined by measuring the oxygen permeation
in a series of containers with different scavenging
polymer-to-concentrate ratios. The containers were sealed with a
glass plate in a low oxygen chamber. The initial headspace oxygen
inside the containers was about 1-2%. The headspace oxygen
concentration was measured periodically by a non-invasive oxygen
analyzer sold by Oxysense Inc. to obtain the oxygen permeation
rate. The headspace oxygen of the APET control container increased
with time while that of the multi-layer container showed reduced
oxygen permeation or even negative permeation.
This experiment was first conducted 14 days after the containers
were made. The same experiment was repeated 71 days after the
containers were made. From FIGS. 24-26. It is determined that the
containers after 71-day storage absorbed oxygen immediately while
those after 14-day storage had an initial positive oxygen
permeation due to the incubation time of oxygen absorption. The
transition time of changing from positive permeation to negative
permeation is determined by the incubation time.
The transition time based on the first experiment (14-day storage)
is summarized in the table shown in FIG. 27. As can be seen from
these experiments, the transition time increases with the
scavenging polymer-to-concentrate ratio.
Certain embodiments of the multi-layer container disclosed herein
are defined in the examples herein. It should be understood that
these examples, while indicating particular embodiments of the
invention, are given by way of illustration only. From the above
discussion and these examples, one skilled in the art can ascertain
the essential characteristics of this invention, and without
departing from the spirit and scope thereof, can make various
changes and modifications of the invention to adapt it to various
usages and conditions. Various changes may be made and equivalents
may be substituted for elements thereof without departing from the
essential scope of the invention. In addition, many modifications
may be made to adapt a particular situation or material to the
teachings of the invention without departing from the essential
scope thereof.
* * * * *